With the advent of the mobile harvester-thresher a problem arose as to what should be done with the by-product material of threshing leaving the rear outlet thereof. In some cases it was desirable to leave the material in a windrow so that it could be gathered for storage by raking or by compressing and tying it in bales. In other cases it was considered desirable to spread the straw portion evenly so that it could more easily be returned to the soil by cultivation. With the trend to little or zero cultivation taking place it became increasingly necessary to more evenly distribute the straw and the chaff up to 40 feet.
Various devices have been devised to scatter the straw and chaff to avoid the inevitable buildup along a narrow path, two such devices are disclosed in Canadian patent 1,179,567 and in U.S. Pat. No. 4,617,942. The patent "567" teaches a harvester-thresher with a chaff spreading apparatus comprising two fans surrounded by a shroud and placed in the vicinity of the grain shoe for receiving chaff therefrom and a separate straw chopper and straw spreader underneath the rear of the harvester-thresher where the straw is ejected from the straw walkers. Applicants device is considerably different in that it does not require two chaff spreading fans with a double shroud located remotely from the straw spreader but is a single integral unit comprising a straw spreader and chaff fan driven by a single motor all in one location. The United States patent "942" teaches dual straw spreaders, dual choppers and spreaders and dual hydraulic drive motors. Applicants device teaches a single straw spreader and chaff distributing fan driven as an integral unit by a single variable speed hydraulic motor. The amount of straw reaching the chaff spreader can also be controlled by removing or adding the readily removable flails.